The present invention relates to the field of internal combustion engines, more particularly to a method of controlling the engine intake and exhaust valves so as to produce a more efficient combustion process within the cylinder and to operate the engine as a pneumatic hybrid.
This invention describes a method for increasing the flexibility of the present valve control. While the general principles and teachings disclosed are applicable to all valve controlled internal combustion engines, the invention is hereinafter described in detail in connection with its application to a reciprocating, cam and valve, multi-cylinder engine.
The poppet valve driven by a camshaft has been used in the internal combustion engine for many years. Modifications to the valve train have been developed to permit changing the valve timing while the engine is in operation. When the timing control prevents the valves from opening during an engine cycle, the cylinder is disabled, and the effect of a variable displacement engine is obtained. The advantage of a variable displacement engine is that when less than maximum efficiency power is required, some of the cylinders may be disabled and the remaining active cylinders' power is increased so that they will operate at greater efficiency, while the engine output remains constant. This approach has had limited success in practice because the usual control activates or deactivates half the number of cylinders, and this abrupt change in output torque causes poor drivability. Furthermore, the disabling mechanism is relatively slow acting so that more than one revolution of the crankshaft is required to make the change.
All of the differences cited with the prior art referenced in my previous applications (Ser. Nos. 09/519,635 & 09/585,778) apply to the present invention. Another example of prior art is the FINGER FOLLOWER ROCKER ARM SYSTEM in U.S. Pat. No. 5,653,198 by Diggs issued Aug. 5, 1997. This invention describes a disabler mechanism controlled by a rotary solenoid with the camshaft providing the power to move the valve. The rotary solenoid shifts the follower away from the cam so no force is transmitted to the valve stem. The shape of the cam lobe still determines the valve action when activated. The intent of the invention is to engage and disengage the cam during the time when the valve is inactive as shown in FIG. 7, because of the high forces involved with valve action. The conventional cam lobe is shaped to accelerate and decelerate the valve at a given time in the engine cycle, and this system cannot change those times. The present application does not have these limitations. The spring energy taken from the camshaft is stored for release at any time to separately open and close the valve, and the valve accelerations are determined by the interchange of energy between two springs. The resonant oscillation between the two springs insures a "soft" valve landing at the oscillation extremes whenever the springs are released.